Mechanical clearance regulator



Feb- 20, 1934- 0. M. BURKHARDT 1948063 MECHANICAL CLEARANCE REGULATOR Filed Aug. 17, 1932 @y 2. Ilzyfl.

' INVENTR 8 Orro /vf` .BuRK//Akpx ATTORNEY Patented Feb. 20, 1934 siren STATES MECHANCAL CLEABNCE @tto M. Burkhardt, Cleveland, hio, @retener to Thompson Produc-teg inc., @levels-end, @hie Application-leugnet l?,

This invention relates to the art ci internel combustion engines and more especially to a mechanical clearance regulator for use in conriec= tion with the valve mechanism.

As is Well known to those who are familiar with the art or internal combustion engines. the overhead valve construction requires frequent adjustment to insure a definite clearance between the valve and its actuating member, the conventional cam. This clearance is necessary to allow for expansion of the linkage between this cam and the valve.

If this clearance diminishes either because of expansion of the valve and its linkage or because of valve seat erosion, then the engine will not function properly because a change of this clearance involves an unfavorable change in the valve timing. This clearance often becomes less than necessary when the engine is working hard. In 2@ this case the valves Willnot seat properly and 'wili leak, causing loss of power.

Because of improper` seating of the valve or the entire lack of seating, the valve is deprived oi' a most essential cooling period during its contact with the water cooled seat in the combustion chamber. Lack of cooling will aggravate the heating of the valve and cause further expansion and consequently worse seating; The valves will then start to warp, burn, and crack. This is often followed by breaking oft of the valve head which in turn causes serious damage to the en gine.

if the clearance between the valve and its actuating members increases either due to normal Wear o the cooperating members or due to a differential in expansion of these members and their supports, as occurs always during the warm-up periods oi the engine, then the valve mechanism becomes objectionablynoisy.

As is well.l known, the water in the cylinder jacket of an internal combustion engine will heat at a comparatively rapid rate in the performance =-of its function as a heat-absorbing or cooling medium for the operating engine. .In fact, it is desirable that the engine attain as rapidly' as possible a certain amount ot heat which is necessary for most efficient operation. But the temperature of the oil which usually bathes the entire valve mechanism and thereby controls its expansion, will not rise as rapidly as that of the Water, and consequently there is a differential in this respect as between the expansions of the water-cooled and oil-bathed cooperating mem-'- bers during the warm-up periods of the engine.

Strictly speaking, a warm-up period follows pension end contraction have a detrimental. er e@ iect upon the proper functioning of the valve mechanism and aggravate weer and erosion. These toets are all well known to those who are familiar with internal combustion origines, and it is these obiectionable conditions which the e@ present invention successfully corrects.

The general object, therefore, of the present invention is to provide a means whereby the clearance between the parts of the valve-operating mechanism will be at every engine revoluw tion autornaticelh/ regulated so as .to preclude the many objectionable features above referred to. These desirable results `are accomplished during Warm-up and cooling-off periods Qof operation as well es at all other times. Thus, this invention ensures quiet and eiiicient operation of valves at all times, and safeguards internal combustion engines against possible serious damage, especially engines of lthe overhead vvalve 8@ Although the invention herein set forth is especially important in the overhead valve type of engine, yet the principle of this invention may be employed in other types of valve construction and it is therefore not to he understood as being es limited to the overhead valve type exclusively.

Among prior attempts to correct these objectionable features, which are relieved by my present invention, there are hydraulic devices in which oil is employed as en operating medium. on Because of certain conditions peculiar to the use of a hydraulic operating medium, as for instance, the need of numerous troublesome check valves and because of the need of dash pots which will leak variable amounts for variations in workto manship, material, normal wear and temperature, the hydraulic type or' device is not entirely dependable. Furthermore, hydraulic devices are costly to manufacture, troubles arelocated only' with diiiiculty, and they are dimcult to repair.

As previously emphasized, the temperature of 'the oil rises more slowly than that of the Water.

During initial warm-up periods when the oil temperature lags considerably behind the tem' perature ofthe water, there is the most urgent me need for a clearance regulator. and during these periods, as well as at all other times, a strictly mechanical regulator is much more eiicient and dependanble thanthe hydraulic type oi.' device.

'I'he hydraulic compensating devices are least 110 efficient during the initial wwup period bea cause the comparatively cold oil is too viscous and will not flow through small check valves.

The necessarily light springs under the plungers gi within. the dash pots are not capable of lifting these plungers, greater force being required to move parts covered with or submerged in very cold oil. This prevents the proper functioning of such hydraulic devices.

ln the present form of device, which is of a strictly mechanical nature, there are overcome, even during warm-up periods of `operation of the engine, the objectionable features just referred to and this constitutes one of the primary objects of Athe present invention.

Whereas, in the familiar overhead valve mechanism, there .is provided and there is always nec, essary, a `certain degree of actual clearance be@ tween the valve and its actuating linlraga es above explained, the present device is so constructed and operates in such manner that there is no actual clearance between cooperating parts other than that required for an oil hlm; but instead there is obtained a relative motion between liti iid

fere with the timing events occurring at the proper moment with regard to .piston position as well as kinetic energy within the valve linkage. Theregulation of opening and closing events of the valve takes place during all periods of operation of the engine, including the warming-up periods. This feature constitutes another object of my present invention.

Still another object consists in devising en automatic clearance regulator which will operate dependably and in a most emcient manner for all conditions of the throttle and regardless of the Speed of operationv of the valve mechanism.

Other objects will appear from the following description and claims when considered together with the accompanying drawing.

Fig. 1 is a partial, transverse sectional view through the cylinderhead and the engine bloei; upon which my invention is provided, this View being taken upon line 1-1 of Fig. 2;

Fig. 2 is a partial view taken at ninety-degrees to Fig. i;

Fig. 3 is a partial top plan view;

Figs. 4 and 5 are taken on lines 4-4 and 5-5. respectively, of Fig. i;

Iig. 6 is a perspective view of one of the carrs; an l Fig. 7 is e. perspective view of one of the resilient supports for the cams.

In the accompanying illustration, the cylinder head 1, the valves 2 and valve stems 3 andthe push rods 4 and cam shaft 5, are all of vsubstantially conventional form. Likewise the valve stems 3 are each surrounded by the usual coil spring 6 which supplements the control of the valve.

The rocker arms 7 as well as the other parts of the present improved mechanical clearance 76 regulator, now to be described in detail, are eselo the valve and its linkage, giving the advantage of actual lash between the parts, but without any are eliminated such factors as ordinarily inter this curved surface would cause a rotation of masthead sentially of duplicate construction for all of the intake and exhaust valves of the engine.

Extending the full length of the cylinder head and supported at intervals by suitable brackets, is a :dried shaft 3 which through thel medium of eccentrics 9 alords support for the rocker arms 'l'. Each rocker arm is provided with an integrally formed collar or hub portion 'le about the axis of which the rocher arms 7 are adapted to, turn. lhe center of the hub *le is so located as to obtain the desired relation between the push rod and valve motion. Within the collar portion 'la there is provided' the eccentric 9 which is mounted upon the stationary shaft 8. An anti-friction bearing 9B is provided between the collar 'l and eccenE tric il.

Flhe one-end of the rocher arm 7 is provided 'with a portion having engagement with the upper end of the valve stem,'while the other end of the rocher arm is provided with the conventionally adjustable screw member ll having the loclc nut 12 and the ball and socket engagement 13 with the upper end of the push rod li.

The eccentric 9 has rigidly attached to it or is formed integrally with the lever arm 14 which extends downwardly and outwardly therefrom, as viewed in Fig. 1 of the drawing. The lower end portionlof this lever arm 14 is formed as a clevis to receive the fiatsided cam l5. In the present illustration, this lever arm is shown in the form of two parallel plates fixed to the eccentric. The cam 15 is pivotally mounted upon a sleeve 16 which is .ixed with a tight fit in openings in the arms of the clevis at the lower end of the lever arm 1c. Extending through il@ the inside of the sleeve 16, there is a coil spring 17 which is attached at its one end to the pin 18 in the cam 15 and is anchored at its other end in an aperture through the wall of the xed sleeve 16 near the end thereof, as indicated at llo reference numeral 19.

Cam 15 bears upon a flexible support 20 which is secured to the top of the cylinder head, as indicated at 2l. The flexible support 20 is so formed and fastened as to permit of resilient i action when pressure is applied thereto through cam 15, which pressure originates from and bears direct relation to the forces necessary to open and close the valve.

y The function of the coil spring 17 is such that i125 when more clearance than the thickness of an loil film develops in the linkage, it will automatically turn the cam 15 counter-clockwise about its axis and hold the spirally curved surface of cam 15 in contact with support 20. The curved 130 surface of cam l5, as will appear from the drawing, may follow either the laws of a spiral, an

' involute or some other suitable contour which insures that a pressure exerted on any part of la this cam 15 about sleeve 16 if there were no friction or if the friction were otherwise overcome. Without a tangential force, which would help to overcome friction, cam 15 is self-locking against rotation on. sleeve 16 for any pressure between cam 15 and its support 20 and for any position' cam 15 may take relative to support 20 through the influence of spring 17 and its relationship to the other members. The self-locking feature of cam 15 is obtained by selecting for it a suitably curved contour and by virtue' of the frictional resistances of the contacting -surfaces of cam 15 with sleeve 16, support 20,

and the sides of the clevis in lever erm 14.

It is to be understood that, accordingto the nueces operation of my present improved form of dei vice, the opening and 'closing of the valve take place during what I have termed the valveoperating period, after which there follows the post-operating or clearance-regulating period. This will be more clearly understood from the following.

Referring to the drawing in which the valve is shown in closed position, the opening ofthe valve 2 will be caused by the rotation of the cam shaft 5 so as to engage and operate the push rod 4 which has operative engagement with the one end of the rocker arm 7. Such action hasv a tendency to turn the rocker arm'7 about its own center in a clockwise direction so that the other end of the rocker arm may actuate the valve stem 3 for opening thevalve. 4

Although full opening of the valve is followed by reversal of motion of .the valve stem, spring 6, rocker arm, and push rod, yet the direction of forces initiated during the opening, upon the support for rocker arm 7, which is utilized for the operation of the clearance regulator, continues as before. Continuation of an upward force on the support of the rocker arm is pro` vided for in the design of the mechanism.

As viewed in Fig. 1, the axis of the rocker armis to the right of the axis' of rotation oftion of the eccentric, and will thereby cause the1 eccentric and lever arm 14 to turn counterclockwise about the axis of fixed shaft 8, and thereby slightly raise the rocker arm 7 bodily upward and simultaneously the arcuate motion of the lower end of lever arm 14, will cause the lever arm 14 to exert' pressure upon the flexible support 20, that is, through the cam 15. Such counter-clockwise movement of the lever arm 14 will determine and limit turning movement of the otherwise self-locking cam 15 and as a result, the distance between the axis of the cam 15 and its flexible support 20 will be diminished, thereby permitting the previously mentioned relative mot tion between the valve and its linkage.

K The slight raising of the rocker arm during the operating period of the valve, as above explained,

produces what is here referred to as virtual lash tation of the'cam- 15 to describe an arc about the axis of the fixed shaft 8. The mechanism is designed so that this arcuate movement will afford desired magnitudes of horizontal and vertical components with respect to the flexible support 20.

It is to be understood that the upward force upon the under side of eccentric 9 together with the magnitude of its eccentricity determine the turning movement of lever arm 14 which transfers the energy to flexible support 20. Stating the above more in detail, the mechanism. transfers a part of the energy available during the valveoperating period to the flexible support 20 for storage. Following the valve operating period, this stored energy is utilized to effect the clearance regulation through the cooperation of the respective parts of the linkage. This period of regulation is also elsewhere herein referred to as post-valve-operating period.

The horizontal component of the arcuate motion of lever arm 14 causes rolling of the cam 15 -upon its support and as already explained, this turning of the cam 15' serves to reduce the distance between the lower end of the lever arm 14 and the flexible support 20 so as to accommodate the counter-clockwise movement of the lever arm and the consequent elevation of the rocker arm for the creation of virtual lash during the valve-operduring the operation of the valve. The magnitude f of the force pressing cam 15 against support 20 together with the magnitude of the vertical component of the arcuate'motion controlled by the flexibility of` support 20 are a direct measure of the energy stored in support 20 for the purpose of clearance. regulation.

'I'he magnitudes of the horizontal and vertical components can be varied through design changes to meet various requirements of clearance regulation inengines differing in design and duty. This is made possible through proper choosing of the eccentricity for eccentric 9, the length for the lever arm 1-4, the contour forcam 15, and the resilience of spring 17 and flexible support 20.

As soon as the valve is closed, the forces which caused the angular motion of the lever arm 14 and the yielding of lsupport 20 are zero. l energy previouslystored up in the exible support, due to its yielding, is now available and through pressure on cam 15, returns the lever arm 14 together with its member parts into their original position if no expansion or contraction of the linkage has taken place. If contraction or expansion of the linkage has taken place, the lever arm will return until stopped by the new location of hub 7 of rocker arm 7 through the medium of eccentric 9. The amount which cam 15 has rolled relative to support 20 is now regulated inasmuch as spring 17 .will return cam 15 to a position which insuresV absence of clearance at all contactingv surfaces within the valve linkage.

Thus, this device is automatically compensating for any set of conditions as might be caused at any time by factors oftemperature, lack of proper adjustment or wear ofthe parts.

'Ihe flexible support 20 is constantly under more or less tension so asv to afford a permanent force to supplement that of the coil springv17 in automatically compensating at any ltime for any abnormal condition which would otherwise prevent proper operation of the valve mechanism, as above explained. Accordingly, the coil spring 17 must also always be under more or less tension and this spring aswell as the flexible support 20 must be of proper relative strength for'operating in the manner herein set forth.

'Asabove explained, the virtual lash created during the operating period` of the valvel is utilized during the closing operation and has the effect of ensuring complete closing of the valve without requiring full releasing movement of the cam shaft 5. In other words, this virtual lash has the advantage of actual lash as a means of ensuring complete closing of the valve but without the disadvantage of noise resulting from actual lash, as above explained. During the clos- The ggg.

ing operation, as well as at all other times, the rocker arm is in actual engagement with the valve stem, without however any hindrance to the functioning of the spring around the valve stem.

With my mechanical clearance regulator, the position of the rocker arm is automatically adjusted so as' to compensate for constantly changing conditions in the valve-operating mechanism at any time, this being made possible bythe creationiof virtual lash and the give and talee action of the mechanism at all times. As a result, there is obtained the highest degree of operating efficiency and practical elimination of the objectionable features hereinbeiore referred to.

Another practical advantage of my improved type of device consists in the fact that it is peculiarly well adapted to be designed particularlyfor diierent engines so as to obtain the proper operative relation between the several mechanical elements of the linkage of emcient clearance regulation in a given engine.

Theoretically, the exible support 20 may not be necessary but the cam l5 may operate efflciently by engagement with an ordinary support for bearing engagement therewith. 'Flexibility within the body of metal-may be all that is required. However, the flexible supportZll will be/ Other advantages will be apparent to those who are familiar with the art to which the present invention relates.

n .the following claims, I have adopted the generic term valve-actuating lever which combut also othertypes of levers employed in dii*- ferent engines for actuating the valve.

What I claim is'. ,f

l. In an internal combustion engine, the conibination with a valve-operating mechanism having a valve-actuating lever arm, of an eccentric upon which said lever arm is mounted for angular movement thereabout, a cam operatively connected with said eccentric, and a substantially stationary abutment for engagement by said cam, said parts being so constructed and arranged that lack of adjustment in the mechanism will be corrected by automatic movement of said eccentric and cain and suchl corrected adjustment will be maintained.

2. ln an internal combustion engine, the combination with a valve-operating mechanism having avalve-actuating lever arm, of an eccentric upon which said lever arm is mounted for angular .movement thereabout, a cam operatively conybination with a valve-operating mechanism having a valve-actuating lever arm, of an eccentric upon which said lever arm is mounted for angular movement thereabout, a rcsiliently actingY cam operatively connected with said eccentric, and a substantially stationary abutment f or engagement by said cam, said cam-,being Amovalgcle'about its axis in. accordance primarily with/the creation of virtual lash by movement of said eccentric by said lever arm during the valve-opening period and only in response to lack of adjustment in the mechanism during the post valve-operating period. f, ,i

el. In an internal combustionengine, the combination with a valveoperating mechanism having a valve-actuatiny'gt'lever arm, of an eccentric upon which said lever/arm is mounted for angular movement thereabout, said eccentric having an arm fixed thereto, a resilientl'y-acting cam oscillatably mounted upon saidlast-named arm, and a substantially' stationary abutment for engagement by said cam, said cam being oscillatable about its axis iii-*accordance primarily with the creation of virtuall lash by movement of said eccentric rby said lever arm during the valveopening period and in response to lack of adjustment in t mechanism during the post valveoperating y/eriod v 5. In adv/internal combustion engine, the combination with a valve-operating mechanismhava valve-'actuating lever,`of an eccentric upon which# said lever arm is mounted for angular' 'movement .ihereabouh resiliently-acting cam means bearing upon a pivot whose axis is a distance away from that of the eccentric, and a substantially stationary abutment for engagement by said cam means, said cam having angular freedom about its axis in accordance primarily with the creation of virtual lash by movement of said leccentric: by said lever arm during the valve-opening period and oniy in response to lack of adjust- Lirne'nt in the mechanism during the post valveopeiating period. prehends not only the rocker arm type of lever "1 d. In an internal combustion engine, the combination with a valve-operating mechanism having a `valve-actuating lever, of a wedge-shaped cam having angular freedom, a spring for nornially forcing said cam towards its larger radius,

a substantially stationary abutment for bearing engagement by said cam, and an operative connection between said lever and cam for turning said cam about its own axis towards the smaller radius thereof during the valve-opening period,

`said parts being so constructed and arranged that said cam will automatically turn towards its larger diameter during the post valve-operating period when and to the extent required for correcting adjustment between the parts of the mechanism.

7. lin an internal combustion engine, the combination with a valve-operating mechanism having a valve-actuating lever arm, oi an eccentric upon which said lever arm is mounted for angular movement thereabout, said eccentric having an arm fined thereto and exlending angularly from its axis, a resiiiently-acting, unsymmetric cam oscilli'italoly mounted upon the extended end oi said last-.named ann, and a substantially stationary abutment for engagement by-said cam.. said cam being oscillatable about its axis in accordance primarily with the creation of. virtual lash by movement of said eccentric `by said lever arm during the valve-opening period and in response to lack of adjustment in the mechanism during the post valve-operating period.

8. in an internal combustion engine, the combination with a valve-operatingmechansmhavtol Hlt

HSID

ffii) gagement by said cam, said cam being oscillatable` mageos faing a valve-actuating lever arm, of an eccentric upon which said lever arm is mounted for angular movement thereabout, said eccentric having an arm fixed thereto and extending angularly from its axis, a' virtually self-locking, resiliently-actingv, automatically-adjusting, unsymmetric cam oscillaiably mounted upon said last-named arm, said cam being normally forced towards its larger radius, and a substantially stationary abutment for bearing engagement by said cam, said cam being oscillatable about its axis and upon its abutment in accordance primarily with the creation of virtual lash by movement of said eccentric by said, lever arm during the valve-opening period and in response to lack of adiustment in the mechanism during the post valve-operating period.

9. In an internal combustion engine, the combination with a valve-operating mechanism having a valve-actuating'lever arm, of an eccentric upon. which said lever arm is mounted for angular movement tliereabout,` said eccentric having an arm fixed thereto and extending angularly from its axis, a virtually self-lockingautomatically adjusting, spiral cam oscillatably mounted upon said last-named arm, a spring normally forcing said cam towards its larger radius, and

a' resilient abutment for bearing engagement byl said cam, said cam being oscillatable about its axis in accordance primarily with the creation of virtual lash by movement of said eccentric during the valve-opening period and being adapted thereby to store energy during said period, and said cam being oscillatable in response .to lack of adjustment in themechanism during the post valve-operating period and being adapted to release such stored energy during said post valve-operating period but only to the extent required by existing conditions at a given time.

l0. In an internal combustion engine, the com bination with a valve-operating mechanism having a rocker arm adapted for operative engagement with a valve stem and a push rod, of an eccentric upon which said rocker arm is oscillatably mounted, a lever arm fixed to said eccentric and extending angularly from its axis, a wedge-shaped cam oscillatably mounted upon said lever arm,spring means arranged between said cam and lever arm for normally forcing said cam towards its larger radius, and a substantially stationary abutment for bearing enabout its axis and upon its abutment in accordance primarily with the creation of virtual lash by movement of said eccentric by said rocker arm during-the valve-opening period and in response to lack of adjustment in the mechanism during the post valve-operating period.-

11. In an internal combustion engine, the combination with a valve-operating mechanism having a rocker arm adapted for operative engagement with a valve stem and a push rod, of an eccentric upon which said rocker arm is oscillatably mounted, a lever arm iixed at its one end to said eccentric and extending angularly from its axis. a spiral cam oscillatablyv mounted upon the other end of said lever arm, spring means arranged between said cam and lever arm 'for normally forcing said cam towards its larger radius, and a substantially stationary abutment for bearing engagement by said cam, said cam being automatically adjustable with oscillating movement about its axis and upon its abutment in accordance primarily with the creation of virtual lash by movement of said eccentric by said rocker arm during the valve-opening period and response to lack of adjustment in the mechanism during the post valve-operating period.

12. In an internal combustion engine, the com-- bination of a rigid shaft, an eccentric oscillatably mounted upon said shaft, a lever arm oscillatablymounted upon said eccentric and adapted for operative engagement as part of the valve-operating mechanism, and.. automatically acting cam means carried by said eccentric and having a substantially stationary abutment and being adapted to regulate the adjustment of said eccentric and thereby regulate thev clearance inl the mechanism. Y

13. In an internal combustion engine, the combination of a rigid shaft, an eccentric oscillatably mounted upon said shaft, a lever arm oscillatablymounted upon said eccentric and adapted for loperative engagement as part of the valve-operating mechanism, an auxiliary lever arm fixed to said eccentric and extending angularly from the axis thereof, a resiliently-acting cam oscillatably mounted upon said auxiliary lever arm,. and a resilient abutment for said cam, said cam being -normally forced towards its larger radius and being adapted to turn about its axis towards its smaller radius in accordance with the creation of virtual lash by movement of said eccentric during the valve-opening period and being adapted thereby to store energy during said period, and said cam being adapted to turn in the opposite direction so as to regulate adjustment of the mechanism during the post valve-operating period, and being adapted to release such stored energy during said post valve-operating period but only toxtlie extent required by existing conditions at a given time.

14. In an internal combustion engine, the combination with a valve-operating mechanism having a rocker arm adapted for operative engagement with a valve stem and a push rod, of a bearing portion provided intermediate the ends 120 of said rocker arm, an eccentric oscillatably mounted upon a fixed support, said rocker arm having its bearing portion oscillatably mounted upon said eccentric, a lever arm having its one l end 'xed to said eccentric and extending angu- 125 larly with respect to the axis of said eccentric,

a spiral cam oscillatably mounted upon the other end of said lever arm, a resilient abutment for engagement by said cam, and spring means arranged hetween said cam and lever arm so as to 130 normally force said cam towards its larger Ira dius, said parts being so constructed and arranged that said cam will be turned about its axis towards its smaller radius in accordance primarily with the creation of virtual lash by movement ofsaid eccentric by said rocker arm during the valve-opening period and being adapted thereby to store energy during said period, and said cam being adapted to turn inthe opposite direction so as to regulate adjustment of said eccentric and hence adjustment of the mechanism during the post valve-operating period and being f adapted to release such stored energy during said post valve-operating period but only to the extent required by existing conditions at a given I 

